134761-87-8Relevant articles and documents
Preparation and application of cobalt oxide nanostructures as electrode materials for electrochemical supercapacitors
Manteghi, Faranak,Kazemi, Sayed Habib,Peyvandipour, Masoud,Asghari, Ahmad
, p. 76458 - 76463 (2015)
In a reaction between cobalt(ii) and ammonium oxalate in the presence of CTAB or F-127 as surfactant to control the particle size, a cobalt oxalate complex was formed. The precipitate was calcined and the resulting nano cobalt oxide was characterized by Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) methods. The crystalline pure and nano-sized particles had an average size of less than 40 nm. Electrochemical properties were examined by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. A maximum specific capacitance of 351 F g-1 was obtained at a scan rate of 0.85 A g-1 in 2 M of KOH solution for Co3O4@Ni foam electrode (Co3O4@NF). Furthermore, the electrode exhibits excellent cycle life stability, and almost 98.6% of its initial specific capacitance was maintained after 1000 cycle tests.
Doping of Co into V2O5 nanoparticles enhances photodegradation of methylene blue
Suresh,Giribabu,Manigandan,Munusamy,Praveen Kumar,Muthamizh,Stephen,Narayanan
, p. 151 - 160 (2014)
V2O5 nanoparticles doped with different amounts of (x = 2%, 5% and 10%) Co was successfully synthesized by thermal decomposition method with the purpose of enhancing their photodegradation performance under visible light irradiation. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Raman, UV-Vis, photoluminescence (PL) spectroscopy, field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM). The photodegradation property of the prepared pure V2O5 and Co-V2O5 nanoparticles were investigated by using aqueous solution of methylene blue (MB) under visible light irradiation. The obtained results clearly indicated that the amount of Co has significant effect on the photodegradation of MB. Particularly, 10%Co-V 2O5 nanoparticles exhibits enhanced photodegradation property than the pure, 2% and 5%Co-doped samples. A plausible mechanism was put forth for such significant improvements in photodegradation performance of Co-V2O5.
Improved Redox Reaction of Lithium Polysulfides on the Interfacial Boundary of Polar CoC2O4 as a Polysulfide Catenator for a High-Capacity Lithium-Sulfur Battery
Kim, Jin Won,Seo, Gyuwon,Bong, Sungyool,Lee, Jaeyoung
, p. 876 - 883 (2021)
The performance of cobalt oxalate as an electrocatalyst in a lithium-sulfur battery (LSB) is improved owing to the suitable adsorbent properties of sulfur. The adsorption mechanism is elucidated by UV/Vis spectroscopy and surface analysis through X-ray photoelectron spectroscopy. Li2S6 is converted into thiosulfate and polythionate by a catenation reaction on the interfacial boundary of CoC2O4 contacted with carbon. Following this, the active polythionate and short-chained liquid lithium polysulfides (LiPS) bound to the cobalt surface are further reduced as CoC2O4 reduces the overpotential to facilitate the LiPS redox reaction, leading to high specific capacity, lower self-discharge rate, and stable long-term cycling performance.
Evaluation of cobalt oxide, copper oxide and their solid solutions as heterogeneous catalysts for Fenton-degradation of dye pollutants
Shen, Yi,Zhang, Zhihui,Xiao, Kaijun
, p. 91846 - 91854 (2015)
A series of CoO, Co0.75Cu0.25O, Co0.5Cu0.5O and CuO nanoparticles were synthesized via the calcination of corresponding oxalates and further examined as catalysts for the heterogeneous Fenton reaction. The structures of the as-prepared oxides were characterized by field emission electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. The catalytic activity of the oxides was evaluated by the degradation of Congo red. It was found that, among the four catalysts, Co0.5Cu0.5O showed the best catalytic performance. Subsequently, the effects of operating parameters including the substrate concentration, pH, H2O2 concentration and reaction temperature in the catalytic performance of the Co0.5Cu0.5O were systematically studied. Under optimized conditions of catalyst loading = 200 mg L-1, pollutant concentration = 100 mg L-1, H2O2 concentration = 3 wt%, temperature = 30 °C and pH = 9, the Co0.5Cu0.5O catalyst could completely degrade the Congo red within 60 min. The degradation products were analyzed by a liquid chromatography-mass spectrometer and the degradation pathway was revealed. To investigate the catalytic mechanism, the pH and concentrations of H2O2 and metal ions were monitored during the Fenton process. Mechanistic studies revealed that hydroxyl radicals and superoxide radicals derived from the activation of H2O2 molecules by metal centers were mainly responsible for the degradation of Congo red, and that copper ions played a critical role in the superior catalytic performance of the Co0.5Cu0.5O catalyst. The Co0.5Cu0.5O catalyst showed negligible metal leaching and outstanding recyclability, which are highly favorable for the practical application in the Fenton process.
Very fast crystallisation of MFe2O4 spinel ferrites (M = Co, Mn, Ni, Zn) under low temperature hydrothermal conditions: A time-resolved structural investigation
Dolcet, Paolo,Diodati, Stefano,Zorzi, Federico,Voepel, Pascal,Seitz, Christoph,Smarsly, Bernd M.,Mascotto, Simone,Nestola, Fabrizio,Gross, Silvia
, p. 2257 - 2268 (2018)
MFe2O4 spinel ferrites (M = Co, Mn, Ni, Zn) were synthesised through a low-temperature aqueous route combining co-precipitation of oxalates and hydrothermal treatment at 135 °C. With the objective of gaining a deeper understanding of the structural evolution of the compounds to crystalline materials during the synthetic process, samples were prepared within different reaction times, showing in most cases a fully crystalline habit already after short treatment times. The resulting solids were characterised through several state-of-the-art analytical techniques, both on the atomic (XAS) and mesoscopic (XRPD, SAXS) scales. In parallel, temperature-programmed characterisation was carried out to investigate the evolution of the compounds during the heating process.
Facile synthesis of Co3O4 nanochains and their improved TEA sensing performance by decorating with Au nanoparticles
Jin, Honghong,Sun, Guang,Zhang, Bo,Luo, Na,Li, Yanwei,Lin, Long,Bala, Hari,Cao, Jianliang,Zhang, Zhanying,Wang, Yan
, p. 782 - 790 (2019)
A novel chain-like nanostructure of Co3O4 was successfully prepared via a facile and reliable oxalate sacrificial template route, in which coralloid cobalt oxalate (CoC2O4·2H2O) precursor was first obtained through a room-temperature precipitation method and then used as sacrificial template to prepare Co3O4 by annealing at 500 °C. Au nanoparticles-decorated Co3O4 nanochains were also prepared by soaking the CoC2O4 precursor in Au+ solution before the annealing process. The prepared samples were characterized by XRD, FESEM, TEM, and N2 adsorption-desorption. Results indicated that the pure and Au-decorated Co3O4 nanochains were constructed by several end-to-end connected nanoparticles, and their specific surface areas were 28.42 m2/g and 37.39 m2/g, respectively. The gas sensing properties of the prepared samples were tested and compared. It was found that after being functionalized with Au nanoparticles, the Co3O4 nanochains showed an improved TEA sensing performance, such as lower optimal working temperature, higher response, and faster response and recover speed. In addition, the Au/Co3O4 sensor can also give a good linearity in the TEA concentration range from 10 to 200 ppm and considerable stability within 7 weeks, suggesting its potential application for quantitative detection of TEA. The improved gas sensing mechanism of the Au/Co3O4 nanochain was discussed.
Co3O4 nanoplates: Synthesis, characterization and study of optical and magnetic properties
Farhadi, Saeed,Pourzare, Kolsoum,Bazgir, Sedigheh
, p. 632 - 637 (2014)
The selective synthesis of spinel-type Co3O4 nanostructure with nanoplates morphology was successfully achieved by solid-state thermal decomposition of the [CoII(NH3) 6](C2O4)·4H2O complex at 350 C without employing any solvent, surfactant and complicated equipment. The product was characterized by thermal analysis (TG/DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, UV-visible spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and magnetic measurements. The TEM images show that the product has a plate-like shape with length of 50-200 nm and thickness of 10-20 nm. FT-IR, XRD, EDX and VSM results suggest the as-prepared Co3O4 nanoplates are pure and single-phase with a weak ferromagnetic behavior. The optical spectrum indicated two direct band gaps at 2.18 and 3.55 eV with a blue shift compared with the bulk samples. The plausible pathway for the formation of Co3O 4 nanoplates was also proposed. Under the present reaction conditions, the decomposition of other cobaltammine complexes and CoC 2O4×2H2O led to the Co3O 4 nanoparticles and nanorods, respectively.
Chalcogenide and pnictide nanocrystals from the silylative deoxygenation of metal oxides
Lin, Chia-Cheng,Tan, Shannon J.,Vela, Javier
, p. 20351 - 20358 (2017)
Transition metal chalcogenide and pnictide nanocrystals are of interest for optoelectronic and catalytic applications. Here, we present a generalized route to the synthesis of these materials from the silylative deoxygenation of metal oxides with trimethylsilyl reagents. Specific nanophases produced in this way include Ni3S2, Ni5Se5, Ni2P, Co9S8, Co3Se4, CoP, Co2P, and heterobimetallic (Ni/Co)9S8. The resulting chalcogenide nanocrystals are hollow, likely due to differential rates of ion diffusion during the interfacial phase transformation reaction (Kirkendall-type effect). In contrast, the phosphide nanocrystals are solid, likely because they form at higher reaction temperatures. In all cases, simultaneous partial decomposition of the deoxygenating silyl reagent produces a coating of amorphous silica around the newly formed nanocrystals, which could impact their stability and recyclability.
CRYSTAL STRUCTURE OF THE ORDERED PHASE OF ZINC OXALATE AND THE STRUCTURE OF ANHYDROUS Fe2+, Co2+, Ni2+, Cu2+, AND Zn2+ OXALATES
Kondrashev, Yu. D.,Bogdanov, V. S.,Golubev, S. N.,Pron', G. F.
, p. 74 - 77 (1985)
Conditions were found for the preparation of ordered phases of Fe2+, Co2+, Ni2+, and Zn2+ oxalates.The powder pattern was used to determine the structure of the ZnC2O4 phase using 62 reflections obtained with λCu Kα radiation and refinement by the full-matrix method of least squares to R = 0.12 (space group P21/n, Z = 2).This structure consist of cation-anion chains connected by Zn-O bonds in a three-dimensional framework.The zinc ion has octahedral coordination and the oxygen atoms differ in the number of their bonds with the cation, leading to inequality in the C-O bond lengths in the C2O42- anion (1.40 and 1.15 Angstroem).The unit cell parameters were found and refined for all the ordered phases.Indexing was carried out for the powder patterns of the disordered isostructural CuC2O4 phases with superpositional structure.
Improved high rate performance and cycle stability for LiNi0.8Co0.2O2 by doping of the high valence state ion Nb5+ into Li+ sites
Wu, Kang,Jia, Guofeng,Shangguan, Xuehui,Yang, Guowei,Zhu, Zenghu,Peng, Zhengjun,Zhuge, Qin,Li, Faqiang,Cui, Xiaoling
, p. 700 - 709 (2018)
High rate performance has been a challenging issue for LiNi0.8Co0.2O2 material. Elemental doping is a very effective method that has been used to maintain the structure of cathode materials with high stability and improve the high rate performance. Encouraged by previous research and considering the shortcomings of LiNi0.8Co0.2O2, materials with a composition of Li1-xNbxNi0.8Co0.2O2 (x = 0, 0.01, 0.03) were prepared by co-precipitation and the solid phase sintering method. The structure and electrochemical performance were studied in detail. The results from structural analysis suggested that the doping element was successfully doped into LiNi0.8Co0.2O2. Electrochemical measurements suggested that high rate capacities led to distinct improvements for a moderate Nb-doping content. Specifically, the initial capacities delivered by LiNi0.8Co0.2O2 and Li0.99Nb0.01Ni0.8Co0.2O2 increased from 97 to 156 mAh/g at 25 °C and 62.1 to 144.7 mAh/g at 50 °C at a rate of 5 C. In addition, the results from differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis demonstrated that the Nb-doped LiNi0.8Co02O2 had a higher thermal stability in the charged state compared to the un-doped material. Therefore, the Li+ sites in LiNi0.8Co0.2O2 were partially substituted by the high valence element Nb, which can lower Li/Ni mixing and polarization, accelerate the migration rate of Li+ and stabilize the structure of the cathode material, thus improving the high rate performance and cycling stability.
